Not applicable.
Not applicable.
This invention relates to a hand tool and more particularly to a bar clamp having an ergonomic handle.
Hand tools are used to perform a number of tasks. One type of hand tool is a bar clamp typically used to hold two articles together while the articles are secured to one another such as by adhering or welding.
In particular, in a QUICK-GRIP bar clamp sold by AMERICAN TOOL COMPANY and disclosed in U.S. Pat. No. 5,009,134 to Joseph A. Sorensen and Dwight L. Gatzemeyer, a bar clamp has a fixed jaw coupled with a handle/grip assembly. A slide bar is received within and is movable relative to the handle/grip assembly. A movable jaw is secured to the free end of the slide bar and is oriented to face the fixed jaw. The handle/grip assembly includes a handgrip and a trigger handle that pivots with respect to the handgrip. As the U-shaped trigger handle is depressed, the trigger handle moves towards and receives a portion of the handgrip. Simultaneously, a driving lever located within a recess defined by the handle/grip assembly is contacted by the trigger handle so that the driving lever frictionally engages the slide bar and pulls the bar so that the movable jaw is translated toward the fixed jaw. The slide bar is moved incrementally each time the trigger handle is depressed until the articles are clamped between the jaws. A spring biased braking lever prevents movement in the opposite direction when the driving lever is not engaging the slide bar such as, for instance, when the trigger handle is retracted from the handgrip. To unclamp the articles, the braking lever is depressed to allow movement of the slide bar in the opposite direction.
However, the QUICK-CLAMP bar clamp suffers from a number of significant drawbacks. For instance, the contour and profile of the trigger handle causes harmful pressure concentrations on the fingers. Specifically, protrusion on the handgrip oftentimes causes concentrations of pressure at the thumb crotch and thenar eminence of the user""s hand.
Other problems result from using the QUICK-CLAMP bar clamp. For instance, the relationship of the trigger handle to the hand grip creates dangerous pressure points at the distal and terminal ends of the handle. Moreover, the effective length and the width of handle assembly of the QUICK-CLAMP bar clamp make the clamp unsuitable for many users. For example, the width of the handle at the flared distal ends of the trigger handle and handgrip is more than ten centimeters. This width is too great to allow the user""s fourth digit (or ring finger) and fifth digit (or little finger) to grasp the bar clamp when the clamp is used in an upright, gun-like posture. Similarly, when used in an inverted manner, the second digit (or index finger) and third digit (or middle finger) of many users are incapable of grasping the end of the handle. With respect to the length of the handle, while the handle length of the handgrip of the QUICK-CLAMP bar clamp exceeds ten centimeters, the flared shape of the handle diminishes the effective graspable length of the handle by more than two centimeters. This effective length is unacceptable for many larger males, particularly those in the top five percentile for hand size and those operating the bar clamp with gloves on their hands.
In a different vein, the QUICKCLAMP bar clamp also suffers from excessive handle travel. When the trigger handle is depressed, the handle moves for some distance before the driving levers engage the slide bar. This wasted movement requires additional repetitions to translate the slide bar the desired distance and leads to significant hand and forearm fatigue. The cumulative effect of the shortcomings of such prior art bar clamps may lead to temporary discomfort, long lasting pain and even debilitating injuries such as upper extremity trauma.
The present invention generally relates to a handle assembly for a hand operable bar clamp having a fixed jaw, a movable jaw and a drive for translating the movable jaw towards the fixed jaw. The assembly includes a handgrip and a trigger handle. The handgrip having an elongated rear portion has a generally rounded surface and being contoured to complement the natural transverse curve of a human palm. The trigger handle is pivotal with respect to the handgrip. The trigger handle includes an elongated front portion having a rounded front surface and being contoured to complement the natural palmar curve of a set of fingers flexed toward the palm. The shape and contour of the handle assembly cause pressure to be safely distributed across the user""s hand when the handgrip and the trigger handle are grasped and the trigger handle is depressed toward said handgrip.
By providing a hand clamp in accordance with the present invention, numerous advantages are achieved. The shape of the handle maximizes the area of contact between the user""s hand and the grip to more evenly distribute the load of the force across the user""s hand. The long rounded handgrip and trigger handle allow hands of almost all sizes to comfortably wrap around the handle assembly. As a result, less gripping force is required to use the handle of the present invention, and the amount of hand and forearm fatigue associated with extended use of the tool is diminished. The handle is more comfortable when holding and squeezing the handle assembly in both the pistol and inverted orientations. Moreover, the minimum gripping force is increased and the maximum gripping force is decreased to result in a smaller force variation for more comfortable operation of the tool. The bar clamp of the present invention also reduces the amount of handle travel so that the number of repetitions required to move the jaws is reduced. Moreover, the bar clamp of the present invention does not have any of the dangerous pinch points plaguing existing bar clamps.